Ceramic composites comprised of silicon carbide whiskers and alumina powder are well known to prior art. Thus, by way of illustration, U.S. Pat. No. 4,543,345 discloses a silicon carbide whisker-alumina ceramic composite with good fracture toughness.
One problem with the ceramic composites presently available is that they cost from about eighty to one hundred and twenty dollars per pound, a price which makes them too expensive for certain applications.
In 1987, applicant George T. Hida disclosed a process for preparing a silicon carbide-whisker/alumina composite. In his Ph.D. Thesis, which was entitled "Study of Solid-State Aluminothermal Reactions: Influence of Activation and Moderation Processes," which was submitted to the Senate of the Technicron--Israel Institute of Technology in Haifa, Israel in Feb. of 1987, and which was published in Apr. of 1987, a reaction was disclosed in which three moles of silica were reacted with four moles of aluminum and three moles of carbon. The silica reagent was 200/230 mesh fraction quartz sand; the aluminum reagent was 325 mesh aluminum powder; and the carbon reagent was carbon black. Stoichiometric amounts of these reagents were mixed, the mixture was compacted into pellets by cold pressing in a die, and the pressed pellets were placed into a furnace which had been preheated to 720 degrees centigrade and were thereafter ignited.
The process disclosed in Hida's 1987 thesis was a substantial improvement over prior art processes for preparing silicon carbide whisker/alumina composite materials. However, it did not reduce the cost of making the composite down to commercially suitable levels.
It is an object of this invention to provide a process for preparing a pressed silicon carbide whisker/alumina composite at a cost which is substantially cheaper than is currently possible.